AASHTO 4.6.2.1.3 Width of Equivalent Interior Strips

[traderjon]

I'll probably figure it out just after hitting "Submit Post", but I cannot figure out what the difference is between the two variables S and L in this section. S is defined as, "Spacing of supporting components" and L as "Span length of deck". If I am looking at a longitudinal spanning wood deck, would not these two be the same? If they are, why does Table 4.6.2.1.3-1 use both in the various parallel equations? Any insight would be appreciated.

Thanks.